An ink-jet head may have an ink supply channel through which ink is supplied from an ink supply source; a plurality of ink chambers, each having a nozzle to discharge ink and arranged along the ink supply channel; and actuators (e.g., piezoelements) provided in the respective ink chambers. A series of ink chambers arranged along the ink supply channel may also be referred to as “ink chamber sequence.” In addition, ink chambers each having a nozzle are arranged along the ink supply channel, and therefore so are the nozzles. A series of nozzles arranged along the ink supply channel may also be referred to as “nozzle sequence.”
In this ink-jet head, actuators apply pressure to the ink in ink chambers to discharge the ink from nozzles. The resolution of this ink-jet head is determined based on the placement pitch of nozzles (hereinafter referred to as “nozzle pitch”).
In addition, a technique has been known where trapezoid-shaped ink chamber groups, each having a plurality of ink chamber sequences, are alternately provided (see, for example, Patent Literature 1). FIG. 1 is a plane view of ink-jet head 70 disclosed in Patent Literature 1.
As shown in FIG. 1, ink chamber groups 21, each having a matrix of ink chambers, are alternately provided in ink-jet head 70. Ink supply channel 5 is formed between ink chamber groups 21. In addition, each ink chamber group 21 has one piezoelectric element unit having a trapezoid shape in plan view.
If air is mixed into ink in the ink-jet head and nozzles in the ink-jet head clog, the ink-jet head might not discharge ink appropriately. Therefore, it has been suggested that air inclusion and nozzle clogging are prevented by circulating ink in the ink-jet head (that is, by supplying ink from outside and discharging ink from the ink-jet head) (see, for example, Patent Literature 2).